Substrate support chuck cooling for deposition chamber

ABSTRACT

A substrate support chuck for use in a substrate processing system is provided herein. In some embodiments, a substrate support for use in a substrate processing chamber may include an electrostatic chuck having a top substrate support surface and a bottom surface, and a cooling ring assembly having a central opening disposed proximate the bottom surface of the electrostatic chuck, the cooling ring assembly including, a cooling section having a top surface thermally coupled to the bottom surface of the electrostatic chuck, the cooling section having a cooling channel formed in a bottom surface of the cooling section, and a cap coupled to a bottom surface of the cooling section and fluidly sealing the cooling channel formed in the cooling section.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a divisional of co-pending U.S. patent applicationSer. No. 14/187,747, filed Feb. 24, 2014, which claims benefit of U.S.provisional patent application Ser. No. 61/788,508, filed Mar. 15, 2013.Each of the aforementioned related patent applications is hereinincorporated by reference in its entirety.

FIELD

Embodiments of the present invention generally relate to semiconductorprocessing.

BACKGROUND

The inventors have observed that conventional high temperature substratesupport chuck for certain applications are not capable of controllingthe heat input created by lengthy heavy deposition rate processes suchas LED backside deposition of gold (Au) or Gold-tin (AuSn), thickaluminum, or some microelectromechanical systems (MEMS) processes. Forexample, where typical 150 mm semiconductor Physical Vapor Deposition(PVD) processes are less than 1 minute long at elevated temperatures,the LED backside deposition processes, for example, are approximately 6minutes long and must be maintained at relatively low temperatures.However, the increased heat input to the wafer and chuck exceeds whatsome conventional chucks can manage.

Therefore, the inventors have provided embodiments of an improvedsubstrate support chuck.

SUMMARY

Embodiments of a substrate support chuck for use in a substrateprocessing system is provided herein. In some embodiments, a substratesupport for use in a substrate processing chamber may include anelectrostatic chuck having a top substrate support surface and a bottomsurface, and a cooling ring assembly having a central opening disposedproximate the bottom surface of the electrostatic chuck, the coolingring assembly including, a cooling section having a top surfacethermally coupled to the bottom surface of the electrostatic chuck, thecooling section having a cooling channel formed in a bottom surface ofthe cooling section, and a cap coupled to a bottom surface of thecooling section and fluidly sealing the cooling channel formed in thecooling section.

In some embodiments, a cooling ring assembly for cooling a substratesupport may include a cooling section having a top surface, a bottomsurface having a cooling channel formed in the bottom surface, and afirst central opening, and a cap having a second central opening,wherein the cap is coupled to the bottom surface of the cooling sectionand fluidly seals the cooling channel formed in the cooling section, andwherein the first central opening and second central opening aresubstantially aligned.

In some embodiments, a process chamber for processing substrates mayinclude a chamber body having an inner volume, a substrate supportdisposed in the inner volume, the substrate support including: anelectrostatic chuck having a top substrate support surface and a bottomsurface; an annular support ring having a central opening coupled to thebottom surface of the electrostatic chuck; an annular retention ringhaving a central opening disposed within the central opening of theannular support ring; and a cooling ring assembly disposed within thecentral opening of the annular retention ring and proximate the bottomsurface of the electrostatic chuck, the cooling ring assembly includinga cooling section having a top surface thermally coupled to the bottomsurface of the electrostatic chuck, the cooling section having a coolingchannel formed in a bottom surface of the cooling section, and a capcoupled to the bottom surface of the cooling section and fluidly sealingthe cooling channel formed in the cooling section.

Other and further embodiments of the present invention are describedbelow.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present invention, briefly summarized above anddiscussed in greater detail below, can be understood by reference to theillustrative embodiments of the invention depicted in the appendeddrawings. It is to be noted, however, that the appended drawingsillustrate only typical embodiments of this invention and are thereforenot to be considered limiting of its scope, for the invention may admitto other equally effective embodiments.

FIG. 1 is a process chamber suitable for use with the inventivesubstrate support chuck in accordance with some embodiments of thepresent invention;

FIG. 2 is a schematic cross-sectional side view of a substrate inaccordance with some embodiments of the present invention; and

FIG. 3 is a schematic cross-sectional bottom view of a cooling ringassembly in accordance with some embodiments of the present invention.

To facilitate understanding, identical reference numerals have beenused, where possible, to designate identical elements that are common tothe figures. The figures are not drawn to scale and may be simplifiedfor clarity. In this document, relational terms such as first andsecond, top and bottom, and the like may be used solely to distinguishone entity or action from another entity or action without necessarilyrequiring or implying any actual such relationship or order between suchentities or actions. It is contemplated that elements and features ofone embodiment may be beneficially incorporated in other embodimentswithout further recitation.

DETAILED DESCRIPTION

Exemplary embodiments consistent with the present inventionadvantageously provide the ability to process substrates which use lowerprocess temperatures either to maintain certain characteristics of thefilm being deposited, or to limit thermal damage to films alreadydeposited. In addition, embodiments consistent with the presentinvention advantageously provide a substrate support chuck capable ofremoving extra heat from substrate during higher energy processes usedto deposit thick films in reasonable time span, or to deposit difficultto sputter materials. In addition, in exemplary embodiments consistentwith the present invention, the process energy can be advantageouslyincreased without raising the wafer temperature, thereby allowing thedeposition rate to be increased leading to a reduction in process timeand a subsequent increase in chamber productivity.

FIG. 1 is a schematic cross-sectional view of plasma processing chamberin accordance with some embodiments of the present invention. In someembodiments, the plasma processing chamber is a physical vapordeposition (PVD) processing chamber. However, other types of processingchambers that utilize electrostatic chucks may also be used with theinventive apparatus.

The chamber 100 is a vacuum chamber which is suitably adapted tomaintain sub-atmospheric pressures within a chamber interior volume 120during substrate processing. The chamber 100 includes a chamber body 106covered by a dome 104 which encloses a processing volume 119 located inthe upper half of chamber interior volume 120. The chamber 100 may alsoinclude one or more shields 105 circumscribing various chambercomponents to prevent unwanted reaction between such components andionized process material. The chamber body 106 and dome 104 may be madeof metal, such as aluminum. The chamber body 106 may be grounded via acoupling to ground 115.

A substrate support 124 may be disposed within the chamber interiorvolume 120 for supporting and chucking a substrate 101, such as asemiconductor wafer or other such substrate as may be electrostaticallyretained. The substrate support 124 may generally include anelectrostatic chuck 150 (described in more detail below) and a hollowsupport shaft 112 for supporting the electrostatic chuck 150. The hollowsupport shaft 112 provides a conduit to provide process gases, fluids,heat transfer fluids, power, or the like, to the electrostatic chuck150.

In some embodiments, the hollow support shaft 112 is coupled to a liftmechanism 113 which provides vertical movement of the electrostaticchuck 150 between an upper, processing position (as shown in FIG. 1) anda lower, transfer position (not shown). A bellows assembly 110 isdisposed about the hollow support shaft 112 and is coupled between theelectrostatic chuck 150 and a bottom surface 126 of chamber 100 toprovide a flexible seal that allows vertical motion of the electrostaticchuck 150 while preventing loss of vacuum from within the chamber 100.The bellows assembly 110 also includes a lower bellows flange 164 incontact with an o-ring 165 which contacts bottom surface 126 to helpprevent loss of chamber vacuum.

The hollow support shaft 112 provides a conduit for coupling a coolantfluid supply 142, a gas supply 141, a chucking power supply 140, and oneor more RF sources 117 (e.g., an RF plasma power supply and/or an RFbias power supply) to the electrostatic chuck 150. In some embodiments,the RF power supply 117 may be coupled to the electrostatic chuck via anRF matching network 116.

A substrate lift 130 may include lift pins 109 mounted on a platform 108connected to a shaft 111 which is coupled to a second lift mechanism 132for raising and lowering the substrate lift 130 so that the substrate101 may be placed on or removed from the electrostatic chuck 150. Theelectrostatic chuck 150 includes thru-holes (described below) to receivethe lift pins 109. A bellows assembly 131 is coupled between thesubstrate lift 130 and bottom surface 126 to provide a flexible sealwhich maintains the chamber vacuum during vertical motion of thesubstrate lift 130.

The chamber 100 is coupled to and in fluid communication with a vacuumsystem 114, which may include a throttle valve (not shown) and vacuumpump (not shown) which are used to exhaust the chamber 100. The pressureinside the chamber 100 may be regulated by adjusting the throttle valveand/or vacuum pump. The chamber 100 is also coupled to and in fluidcommunication with a process gas supply 118 which may supply one or moreprocess gases to the chamber 100 for processing a substrate disposedtherein.

In operation, for example, a plasma 102 may be created in the chamberinterior volume 120 to perform one or more processes. The plasma 102 maybe created by coupling power from a plasma power source (e.g., RF powersupply 117) to a process gas via one or more electrodes (describedbelow) within the chamber interior volume 120 to ignite the process gasand create the plasma 102. Alternatively or in combination, a plasma maybe formed in the chamber interior volume 120 by other methods. In someembodiments, a bias power may be provided from a bias power supply(e.g., RF power supply 117) to one or more electrodes (described below)disposed within the substrate support or the electrostatic chuck 150 toattract ions from the plasma towards the substrate 101.

In some embodiments, for example where the chamber 100 is a PVD chamber,a target 166 comprising a source material to be deposited on a substrate101 may be disposed above the substrate and within the chamber interiorvolume 120. The target 166 may be supported by a grounded conductiveportion of the chamber 100, for example an aluminum adapter through adielectric isolator.

A controllable DC power source 168 may be coupled to the chamber 100 toapply a negative voltage, or bias, to the target 166. An RF power supply117A-B may be coupled to the substrate support 124 in order to induce anegative DC bias on the substrate 101. In addition, in some embodiments,a negative DC self-bias may form on the substrate 101 during processing.In other applications, the substrate support 124 may be grounded or leftelectrically floating. In some embodiments, an RF power supply 170 mayalso be coupled to the chamber 100 to apply RF power to the target 166to facilitate control of the radial distribution of a deposition rate onsubstrate 101. In operation, ions in the plasma 102 created in thechamber 100 react with the source material from the target 166. Thereaction causes the target 166 to eject atoms of the source material,which are then directed towards the substrate 101, thus depositingmaterial.

In some embodiments, a rotatable magnetron (not shown) may be positionedproximate a back surface of the target 166. The magnetron may include aplurality of magnets configured to produce a magnetic field within thechamber 100, generally parallel and close to the surface of the target166 to trap electrons and increase the local plasma density, which inturn increases the sputtering rate. The magnets produce anelectromagnetic field around the top of the chamber 100, and are rotatedto rotate the electromagnetic field which influences the plasma densityof the process to more uniformly sputter the target 166.

For example, the electrostatic chuck 150 may comprise a dielectricmember having a support surface for supporting a substrate having agiven width (e.g., 150 mm, or other sized silicon wafers or othersubstrates). The substrate support 124 may include a cooling ringassembly 152 disposed beneath the electrostatic chuck 150 to cool theelectrostatic chuck 150. Coolant may be supplied to the cooling ringassembly 152 via a coolant fluid supply 142. The cooling ring assembly152 is discussed below in detail with respect to FIGS. 2 and 3.

FIG. 2 depicts a schematic cross-sectional side view of substratesupport 124. As discussed above with respect to FIG. 1, the substratesupport 124 includes an electrostatic chuck 150. In some embodiments,the electrostatic chuck 150 may be formed from a dielectric materialsuch as a ceramic, although other materials may be used. In someembodiments, a low operating temperature aluminum nitride (for example,AN2010 by KYOCERA) may be used which has a thermal conductivity ofgreater or equal than 150 W/m−K. This greatly aids in the removal ofheat from the substrate 101 and transferring this heat to the coolingring assembly 152.

In some embodiments, a substrate support surface of the electrostaticchuck 150 may have a diameter 230 of about 140 to about 160 mm tosupport a 150 mm substrate 101. In some embodiments, the diameter 230may be about 144 mm to support a 150 mm substrate 101. Other diametersmay be used as desired to support different sized substrates. Theelectrostatic chuck 150 may include one or more lift pin holes 228formed though the body of the electrostatic chuck 150 which may havelift pins disposed therethrough to raise and lower a substrate 101 ontothe top surface of the electrostatic chuck 150. In some embodiments, theelectrostatic chuck 150 may also have a gas hole 222 formed though thebody of the electrostatic chuck 150 which may be used to supply a gas togas channels that may be formed on the top surface of the electrostaticchuck 150, thereby providing the gas to the backside of the substrate101 when disposed on the electrostatic chuck 150.

An annular support ring 212 may be coupled to a backside of theelectrostatic chuck 150. In some embodiments, the annular support ring212, having a central opening, may be brazed or welded to the backsideof the electrostatic chuck 150. In some embodiments, the annular supportring 212 may be fabricated from an iron-nickel-cobalt alloy, or anyother material having a similar coefficient of thermal expansion andstructural properties. An annular retention ring 214 having a centralopening may be disposed within the central opening of the support ring212. The retention ring 214 may be coupled to the annular support ring212.

A cooling ring assembly 152 may be disposed proximate a bottom surfaceof the electrostatic chuck 150 to cool the electrostatic chuck 150. Insome embodiments, the cooling ring assembly 152 has a diameter that issmaller than the substrate support surface of the electrostatic chuck150. In some embodiments, the cooling ring assembly 152 has a diameterthat is smaller than a diameter along which the lift pin holes 228 arelocated. In some embodiments, the cooling ring assembly 152 may bethermally coupled to the electrostatic chuck 150 via a thermal gasket210. In some embodiments, the thermal gasket 210 may be layer ofdirectionally conductive (e.g., vertically) graphite material. Thisadvantageously improves the thermal conduction to the cooling ring.Conventional cooling rings typically rely on contact between the coolingring and ceramic which is not ideal as the surfaces are not 100% flatleading to minute air gaps and poor thermal conductivity. Other thermalgasketing materials are also possible such as thermal paste.

In some embodiments, the cooling ring assembly 152 may include a coolingsection 250 coupled to a cap 252. In some embodiments, the coolingsection 250 may be formed from copper. In other embodiments, othermaterials such as stainless steel, aluminum, or the like may be useddepending on the thermal conductivity desired and the processingenvironment in which the cooling ring 152 will be operating in. In someembodiment, the thermal conductivity of the cooling section is about 300W/m−K or greater. In some embodiments, the cap 252 may be formed fromstainless steel, or other materials that may facilitate welding ofcooling fluid feed tubes. In some embodiments, the cooling section 250and cap 252 may be bolted, brazed, welded, pinned, etc. together. Insome embodiments alignment pins 218 may be used to align the coolingsection 250 and cap 252.

The cooling section 250 includes a coolant channel 258 for flowing acoolant therethrough. As shown in FIG. 3, which is a schematic view ofthe bottom of cooling section 250, a first end of the coolant channel258 may be couple to a first cooling supply tube 302 for providingcoolant to the cooling section 250. In some embodiments, the coolant mayflow through coolant channel 258, which may be formed as a groove in thebody of the cooling section 250 in a serpentine configuration. A secondend of the coolant channel 258 may be coupled to a cooling fluid outlettube 304 to remove the heated coolant from the cooling ring assembly152. In some embodiments, the cap 252 is coupled to the cooling section250 in such a way to prevent the coolant from leaking from coolantchannel 258. In some embodiments, the cap 252 may include a centralopening 262 that aligns with and has the same shape and size as opening254 in the cooling section 250.

In some embodiments, the cooling section 250 may include a plurality ofopenings 256 with alignments pins 216 disposed therein for aligning thecooling ring assembly 152 to the electrostatic chuck 150. The coolingring assembly 152 may have an central opening 254 disposed through boththe cooling section 250 and cap 252 to allow for variouscontacts/piping/connections to the electrostatic chuck 150 to passthrough. For example, in some embodiments, spring-retained thermocouples220 may pass through opening 254 to connect to a backside of theelectrostatic chuck 150. Similarly, in some embodiments, gas/electricallines 232 may pass through opening 254 to connect to the electrostaticchuck 150. The cooling ring assembly 152 may include a plurality offastener holes 260 disposed about an outer diameter of the ring assembly152.

While the foregoing is directed to embodiments of the present invention,other and further embodiments of the invention may be devised withoutdeparting from the basic scope thereof.

The invention claimed is:
 1. A cooling ring assembly for cooling asubstrate support, comprising: a cooling section having a top surface, abottom surface having a cooling channel formed in the bottom surface,and a first central opening, wherein the cooling section is formed froma material having a thermal conductivity of greater or equal than 300W/m−K; a cap coupled to the bottom surface of the cooling section thatdirectly covers and fluidly sealing the cooling channel formed in thecooling section, wherein the cap includes a second central opening; anda thermal gasket coupled to the top surface of the cooling section, andwherein the thermal gasket is a layer of vertically conductive graphitematerial, wherein the first and second central openings have anon-circular shape configured to accommodate a plurality of pipingand/or connections to pass through, wherein the second central openingaligns with and has the same shape and size as the first central openingin the cooling section, wherein the cooling channel is formed about aperiphery of the non-circular first central opening.
 2. A cooling ringassembly of claim 1, wherein the cooling channel if formed in aserpentine configuration about a periphery of the first central opening.3. The cooling ring assembly of claim 1, wherein the cap is formed fromstainless steel.
 4. The cooling ring assembly of claim 1, wherein thecooling section is formed from one of copper, steel, or aluminum.
 5. Thecooling ring assembly of claim 1, the cooling section and cap are one ofbolted, brazed, welded, or pinned together.
 6. The cooling ring assemblyof claim 1, further comprising alignment pins that align the coolingsection and cap.
 7. The cooling ring assembly of claim 1, furthercomprising: a coolant supply tube fluidly coupled to a first end of thecooling channel; and a coolant outlet tube fluidly coupled to a secondend of the cooling channel.
 8. A process chamber for processingsubstrates, comprising: a chamber body having an inner volume; asubstrate support disposed in the inner volume, the substrate supportincluding: an electrostatic chuck having a top substrate support surfaceand a bottom surface; an annular support ring having a central openingcoupled to the bottom surface of the electrostatic chuck; an annularretention ring having a central opening disposed within the centralopening of the annular support ring; and a cooling ring assemblydisposed within the central opening of the annular retention ring andproximate the bottom surface of the electrostatic chuck, the coolingring assembly including: a cooling section having a top surface, abottom surface having a cooling channel formed in the bottom surface,and a first central opening, wherein the cooling section is formed froma material having a thermal conductivity of greater or equal than 300W/m−K; and a cap coupled to the bottom surface of the cooling sectionthat directly covers and fluidly sealing the cooling channel formed inthe cooling section, wherein the cap includes a second central opening,wherein the first and second central openings have a non-circular shapeconfigured to accommodate a plurality of piping and/or connections topass through, wherein the second central opening aligns with and has thesame shape and size as the first central opening in the cooling section,and wherein the cooling channel is formed about a periphery of thenon-circular first central opening, wherein the cooling ring assembly isthermally coupled to the electrostatic chuck via a thermal gasket, andwherein the thermal gasket is a layer of vertically conductive graphitematerial.
 9. The process chamber of claim 8, wherein the cooling channelformed about a periphery of the first central opening in the coolingsection.
 10. The process chamber of claim 8, further comprising: acoolant supply tube fluidly coupled to a first end of the coolingchannel; and a coolant outlet tube fluidly coupled to a second end ofthe cooling channel.
 11. The process chamber of claim 8, wherein the capis formed from stainless steel.
 12. The process chamber of claim 8,wherein the cooling section is formed from one of copper, steel, oraluminum.
 13. The process chamber of claim 8, the cooling section andcap are one of bolted, brazed, welded, or pinned together.
 14. Theprocess chamber of claim 8, further comprising alignment pins that alignthe cooling section and cap.
 15. The process chamber of claim 8, whereinthe top surface of the cooling section includes a plurality of openingswith alignments pins disposed therein that align the cooling ringassembly to the electrostatic chuck.
 16. The process chamber of claim 8,further comprising at least one thermocouple disposed through the firstand second central openings and coupled to the bottom surface of theelectrostatic chuck.
 17. The process chamber of claim 16, wherein the atleast one thermocouple is a spring-retained thermocouple.
 18. Theprocess chamber of claim 8, further comprising a plurality ofthermocouples disposed through the first and second central openings andcoupled to the bottom surface of the electrostatic chuck.